The idea of a continuous stream of particles flowing outward from the Sun was first suggested by British astronomer Richard Carrington in 1859. A century later, physicist Eugene Parker said that comet tails always point away from the Sun simply because a “solar wind,” as he called it, pushes on them. Parker was widely ridiculed, and yet in the very next year the Soviet Luna I spacecraft detected such particles whizzing a million miles an hour. Nowadays the solar wind is routinely monitored by a fleet of spacecraft.